Re: [PATCH 6/9] pNFS: Handle NFS4ERR_OLD_STATEID on layoutreturn by bumping the state seqid

[Trond Myklebust <trondmy@hammerspace.com>]

On Thu, 2019-09-12 at 11:14 -0400, Olga Kornievskaia wrote:
> Hi Trond,
> 
> Can you explain why are we just bumping the seqid by 1 instead of
> what
> it was currently using to update it to the current value which could
> be more than off by one? I'm just speculating that we'll see the same
> behavior that we'll get the ERR_OLD_STATEID incremented by one until
> the current value?

We only bump by 1 if we see that we're already above the seqid of the
current layout stateid. Otherwise, we sync to the value of that layout
stateid before retrying.

> 
> On Tue, Sep 10, 2019 at 4:09 AM Trond Myklebust <trondmy@gmail.com>
> wrote:
> > If a LAYOUTRETURN receives a reply of NFS4ERR_OLD_STATEID then
> > assume we've
> > missed an update, and just bump the stateid.
> > 
> > Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
> > ---
> >  fs/nfs/nfs4proc.c |  2 +-
> >  fs/nfs/pnfs.c     | 18 ++++++++++++++----
> >  fs/nfs/pnfs.h     |  4 ++--
> >  3 files changed, 17 insertions(+), 7 deletions(-)
> > 
> > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> > index a5deb00b5ad1..cbaf6b7ac128 100644
> > --- a/fs/nfs/nfs4proc.c
> > +++ b/fs/nfs/nfs4proc.c
> > @@ -9069,7 +9069,7 @@ static void nfs4_layoutreturn_done(struct
> > rpc_task *task, void *calldata)
> >         server = NFS_SERVER(lrp->args.inode);
> >         switch (task->tk_status) {
> >         case -NFS4ERR_OLD_STATEID:
> > -               if (nfs4_layoutreturn_refresh_stateid(&lrp-
> > >args.stateid,
> > +               if (nfs4_layout_refresh_old_stateid(&lrp-
> > >args.stateid,
> >                                         &lrp->args.range,
> >                                         lrp->args.inode))
> >                         goto out_restart;
> > diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> > index abc7188f1853..bb80034a7661 100644
> > --- a/fs/nfs/pnfs.c
> > +++ b/fs/nfs/pnfs.c
> > @@ -359,9 +359,10 @@ pnfs_clear_lseg_state(struct
> > pnfs_layout_segment *lseg,
> >  }
> > 
> >  /*
> > - * Update the seqid of a layout stateid
> > + * Update the seqid of a layout stateid after receiving
> > + * NFS4ERR_OLD_STATEID
> >   */
> > -bool nfs4_layoutreturn_refresh_stateid(nfs4_stateid *dst,
> > +bool nfs4_layout_refresh_old_stateid(nfs4_stateid *dst,
> >                 struct pnfs_layout_range *dst_range,
> >                 struct inode *inode)
> >  {
> > @@ -377,7 +378,15 @@ bool
> > nfs4_layoutreturn_refresh_stateid(nfs4_stateid *dst,
> > 
> >         spin_lock(&inode->i_lock);
> >         lo = NFS_I(inode)->layout;
> > -       if (lo && nfs4_stateid_match_other(dst, &lo->plh_stateid))
> > {
> > +       if (lo &&  pnfs_layout_is_valid(lo) &&
> > +           nfs4_stateid_match_other(dst, &lo->plh_stateid)) {
> > +               /* Is our call using the most recent seqid? If so,
> > bump it */
> > +               if (!nfs4_stateid_is_newer(&lo->plh_stateid, dst))
> > {
> > +                       nfs4_stateid_seqid_inc(dst);
> > +                       ret = true;
> > +                       goto out;
> > +               }
> > +               /* Try to update the seqid to the most recent */
> >                 err = pnfs_mark_matching_lsegs_return(lo, &head,
> > &range, 0);
> >                 if (err != -EBUSY) {
> >                         dst->seqid = lo->plh_stateid.seqid;
> > @@ -385,6 +394,7 @@ bool
> > nfs4_layoutreturn_refresh_stateid(nfs4_stateid *dst,
> >                         ret = true;
> >                 }
> >         }
> > +out:
> >         spin_unlock(&inode->i_lock);
> >         pnfs_free_lseg_list(&head);
> >         return ret;
> > @@ -1475,7 +1485,7 @@ int pnfs_roc_done(struct rpc_task *task,
> > struct inode *inode,
> >                 *ret = -NFS4ERR_NOMATCHING_LAYOUT;
> >                 return 0;
> >         case -NFS4ERR_OLD_STATEID:
> > -               if (!nfs4_layoutreturn_refresh_stateid(&arg-
> > >stateid,
> > +               if (!nfs4_layout_refresh_old_stateid(&arg->stateid,
> >                                         &arg->range, inode))
> >                         break;
> >                 *ret = -NFS4ERR_NOMATCHING_LAYOUT;
> > diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
> > index 3ef3756d437c..f8a38065c7e4 100644
> > --- a/fs/nfs/pnfs.h
> > +++ b/fs/nfs/pnfs.h
> > @@ -261,7 +261,7 @@ int pnfs_destroy_layouts_byfsid(struct
> > nfs_client *clp,
> >                 bool is_recall);
> >  int pnfs_destroy_layouts_byclid(struct nfs_client *clp,
> >                 bool is_recall);
> > -bool nfs4_layoutreturn_refresh_stateid(nfs4_stateid *dst,
> > +bool nfs4_layout_refresh_old_stateid(nfs4_stateid *dst,
> >                 struct pnfs_layout_range *dst_range,
> >                 struct inode *inode);
> >  void pnfs_put_layout_hdr(struct pnfs_layout_hdr *lo);
> > @@ -798,7 +798,7 @@ static inline void
> > nfs4_pnfs_v3_ds_connect_unload(void)
> >  {
> >  }
> > 
> > -static inline bool nfs4_layoutreturn_refresh_stateid(nfs4_stateid
> > *dst,
> > +static inline bool nfs4_layout_refresh_old_stateid(nfs4_stateid
> > *dst,
> >                 struct pnfs_layout_range *dst_range,
> >                 struct inode *inode)
> >  {
> > --
> > 2.21.0
> > 
-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com